Sigma bond

File:Sigma bond.svg

A sigma bond between two atoms

A sigma bond (σ bond) is a type of chemical bond. It is the strongest one of the covalent type. In a sigma bond, the atomic orbitals from two atoms which are nearby go one on top of each other. This is different from a pi bond where they touch sideways. This is why a sigma bond is stronger. Sigma bonds can involve s, p, d or f orbitals. They must however be of the right symmetry to be able to form the bond.

Since the σ bond is strong, the bonding orbital is low in energy. This also means that the antibonding orbital σ* is high in energy.

Sigma Bond Media

• Dihydrogen-LUMO-phase-3D-balls.png

  1sσ* antibonding molecular orbital in H2 with nodal plane

• Electron orbitals crop.svg

  Electron orbitals

• Molecular orbitals sq.svg

  s-q molecular orbital

• Molecular orbital of hydrogen fluoride.svg

  Molecular orbital of hydrogen fluoride

References

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